Physiological and behavioral stress reactions to both environmental, medical and caretaking aspects of the neonatal intensive care unit have been documented in low birth weight infants. An individualized developmental approach to care designed to minimize stress has been associated with improved outcomes. An important component of this approach is changing the way the infant is handled by a) providing physical support; b) providing aids for self-regulation; and c) pacing interventions on the basis of infant response. The purpose of this study is to determine whether developmental handling 1) reduces the incidence of physiological (decreases in peripheral and brain oxygenation, respiratory and cardiac instability, and elevated intracranial blood volume) and behavioral (autonomic/visceral, motor, behavioral state) signs of stress a) during intrusive procedures, and b) during general caregiving and feeding; 2) improves immediate feeding outcomes (feeding distress and feeding efficiency; and 3) is most effective during the early weeks post birth. A quasi-experimental crossover longitudinal design with each subject serving as his/her own control will be used to study a convenience sample of 20 male and 20 female infants with birth weights between 700 and 1500 grams and requiring assisted ventilation. Infants will be assessed while on 1) ventilatory support, 2) after recovery from need for such support, 3) during early nipple feeding, and 4) after complete nipple feeding. At each time period the infant will be monitored during four consecutive caretaking sessions. At Times 1 and 2 each session will involve one intrusive procedure plus routine nursing cares and a feeding; at Times 3 and 4 only routine care and feeding. Order of treatment, developmental versus traditional, will be determined by random assignment. The treatments will be carried out by a trained research nurse using precise protocols. Physiological indices of stress will be monitored polygraphically, and nurse and infant behaviors coded from both direct observation and videotapes. Outcome measures will be examined for effects of handling procedure within time and trends over time, with level of morbidity as a covariate. Support for the hypotheses will contribute to establishing a scientific base for systematic implementation of developmental handling protocols, and thereby help to improve developmental outcomes for very low birthweight infants.